In recent years all-purpose liquid detergents have become widely accepted for cleaning hard surfaces, e.g., painted woodwork and panels, tiled walls, wash bowls, bathtubs, linoleum or tile floors, washable wall paper, etc.. Such all-purpose liquids comprise clear and opaque aqueous mixtures of water-soluble synthetic organic detergents and water-soluble detergent builder salts. In order to achieve comparable cleaning efficiency with granular or powdered all-purpose cleaning compositions, use of water-soluble inorganic phosphate builder salts was favored in the prior art all-purpose liquids. For example, such early phosphate-containing compositions are described in U.S. Pat. Nos. 2,560,839; 3,234,138; 3,350,319; and British Patent No. 1,223,739.
In view of the environmentalist's efforts to reduce phosphate levels in ground water, improved all-purpose liquids containing reduced concentrations of inorganic phosphate builder salts or non-phosphate builder salts have appeared. A particularly useful self-opacified liquid of the latter type is described in U.S. Pat. No. 4,244,840.
However, these prior art all-purpose liquid detergents containing detergent builder salts or other equivalent tend to leave films, spots or streaks on cleaned unrinsed surfaces, particularly shiny surfaces. Thus, such liquids require thorough rinsing of the cleaned surfaces which is a time-consuming chore for the user.
In order to overcome the foregoing disadvantage of the prior art all-purpose liquid, U.S. Pat. No. 4,017,409 teaches that a mixture of paraffin sulfonate and a reduced concentration of inorganic phosphate builder salt should be employed. However, such compositions are not completely acceptable from an environmental point of view based upon the phosphate content. On the other hand, another alternative to achieving phosphate-free all-purpose liquids has been to use a major proportion of a mixture of anionic and nonionic detergents with minor amounts of glycol ether solvent and organic amine as shown in U.S. Pat. No. 3,935,130. Again, this approach has not been completely satisfactory and the high levels of organic detergents necessary to achieve cleaning cause foaming which, in turn, leads to the need for thorough rinsing which has been found to be undesirable to today's consumers.
Another approach to formulating hard surfaced or all-purpose liquid detergent composition where product homogeneity and clarity are important considerations involves the formation of oil-in-water (o/w) microemulsions which contain one or more surface-active detergent compounds, a water-immiscible solvent (typically a hydrocarbon solvent), water and a "cosurfactant" compound which provides product stability. By definition, an o/w microemulsion is a spontaneously forming colloidal dispersion of "oil" phase particles having a particle size in the range of about 25 to about 800 .ANG. in a continuous aqueous phase. In view of the extremely fine particle size of the dispersed oil phase particles, microemulsions are transparent to light and are clear and usually highly stable against phase separation.
This invention relates to a cleaner for hard surfaces, such as bathtubs, sinks, tiles, porcelain and enamelware, which removes soap scum, lime scale and grease from such surfaces without harming them. More particularly, the invention relates to an acidic microemulsion or acidic all purpose cleaning composition that can be sprayed onto the surface to be cleaned, and wiped off without usual rinsing, and still will leave the cleaned surface bring and shiny. The invention also relates to an all purpose hard surface cleaning composition.
Hard surface cleaners, such as bathroom cleaners and scouring cleansers, have been known for many years. Scouring cleansers normally include a soap or synthetic organic detergent or other surface active agent, and an abrasive. Such products can scratch relatively soft surfaces and can eventually cause them to appear dull. Also, they are sometimes ineffective to remove lime scale (usually encrusted calcium and magnesium carbonate) in normal use. Because lime scale can be removed by chemical reactions with acidic media many acidic cleaners have been produced, which have met with various degrees of acceptance. In some instances such cleaners have been failures because the acid employed was too strong and damaged the surfaces being cleaned. At other times, the acidic component of the cleaner reacted objectionably with other components of the product, adversely affecting the detergent or perfume, for example. Some cleaners required rinsing afterward to avoid leaving objectionable deposits on the cleaned surfaces.
As a result of research performed in efforts to overcome the mentioned disadvantages there have recently been manufactured improved liquid cleaning compositions in stable microemulsion form which are effective to remove soap scum, lime scale and greasy soils from hard surfaces, such as bathroom surfaces, and which do not require rinsing after use. Such products are described in U.S. Pat. No. 5,076,954 for Stable Microemulsion Cleaning Composition, which is hereby incorporated by reference.
In particular, Example 3 of that application discloses an acidic, clear, oil-in-water microemulsion which is therein described as being successfully employed to clean shower wall tiles of lime scale and soap scum that had adhered to them. Such cleaning was effected by applying the cleaner to the walls, followed by wiping or minimal rinsing, after which the walls were allowed to dry to a good shine.
The described compositions of U.S. Pat. 5,076,954 are effective in removing lime scale and soap scum from hard surfaces, and is easy to use, but it has been found that its mixture of acidic agents (succinic, glutaric and adipic acids) could damage the surfaces of some hard fixtures, such as those of materials which are not acid resistant. One of such materials is an enamel that has been extensively employed in Europe as a coating for bathtubs, herein referred to as European enamel, zirconium white enamel or zirconium whit powder enamel, which has the advantage of being resistant to detergents, which makes it suitable for use on tubs, sinks, shower tiles and bathroom enamelware. However, such enamel is sensitive to acids and is severely damaged by use of the microemulsion acidic cleaner based on the three organic carboxylic acids, which was mentioned previously. That problem has been solved by the present invention which employs an anticorrosion system of a nitrogen containing organic compound and phosphoric acid in the cleaner with the organic acids, and rather than exacerbating the problem, they prevent damage to such European enamel surfaces by such organic acids. Thus, the present invention allows the cleaning by the invented compositions of European enamel surfaces, as well as any other acid resistant surfaces of bathtubs, and other bathroom surfaces. However, the product should not be used on materials that are especially susceptible to attack by acidic media, such as marble.
In accordance with the present invention an acidic aqueous liquid cleaner for bathtubs and other hard surfaced items which are acid resistant or are of zirconium white enamel, which cleaner is of a pH in the range of 1 to 4, and which removes lime scale, soap scum and greasy soil from surfaces of such items without damaging such surfaces, comprises: a detersive proportion of synthetic organic detergent, which is capable of removing greasy soil from such surfaces; a lime scale and soap scum removing proportion of organic acid(s) having 2 to 10 carbon atoms therein, which group of acids excludes oxalic and malonic acids, an anticorrosion system, with the proportions being such as to prevent damage to zirconium white enamel surfaces of items to be cleaned by the organic acid(s) when the cleaner is employed to clean such items.
U.S. Pat. No. 5,082,584 discloses a microemulsion composition having an anionic surfactant, a cosurfactant, nonionic surfactant, perfume and water; however, these compositions do not possess the anticorrosion effect and the improved interfacial tension properties as exhibited by the compositions of the instant invention.
U.S. Pat. No. 5,192,460 discloses an acidic microemulsion which contains an anticorrosion system comprising a mixture of phosphoric acid aminotris(methylenephosphoric acid).
A major problem in cleaning of enamel hard surface is that enamel surfaces containing high levels of Al and Zr are attached by the acid components of the microemulsion composition thereby causing corrosion of the enamel surface on the hard surface. It is desirably in the cleaning of hard surface to be able to minimize this corrosion. The unique and novel microemulsion and all purpose hard surface cleaning compositions of the instant invention have incorporated therein an anticorrosion system which helps minimize the corrosion on the enamel surface being cleaned.